Dilatation balloons and systems for their dilatation are known in the art in the field of angioplasty, where the balloons are usually used to dilate a blood vessel by inserting the balloon into the blood vessel and inflating it by introducing inflation liquid into the balloon. Such systems and processes are also commonly referred to respectively as catheter balloon and catheterization.
In the course of a catheterization process, a variety of malfunctions may take place including rupture of the balloon, leakage in the balloon and even a rupture of the blood vessel into which the balloon is inserted. In such cases, the inflation fluid may pour into the blood vessel or into the body. For this reason, it is usually desirable to keep the inflation liquid sterilized.
U.S. Pat. No. 5,273,537 discloses an inflation apparatus which is economically returnable to a sterile state after use, and which provides easy, accurate control over pressure within the dilatation balloon.
The inflation apparatus for inflating a dilatation balloon includes a frame having a first receiver supporting the barrel of a syringe. An operator has a second receiver supporting the plunger of the syringe. The syringe includes a fluid port for connecting the syringe chamber to the lumen of the catheter. A motor is supported by the frame and operatively connected to the operator to move the piston to change fluid pressure within said syringe chamber. A release device permits quick release of the pressure in the balloon catheter without the use of the motor. A pressure sensor is mounted to the frame to measure the pressure in the chamber through a diaphragm on the syringe. The pressure sensor operates a microprocessor-controlled display, which provides display of inflation and duration information and calculates other information. A circuit selectively operates the motor. An inflation control connected to the circuit permits operation of the motor at selected rates of inflation/deflation or to selected specific inflation pressures.
In most catheterization processes it is beneficial to use inflation cycles in order to gradually dilate the blood vessel. It is also preferable to maintain a steady inflation/deflation rate for the same reason. For this purpose, a number of motorized catheter systems have been suggested. In some of the latter systems, feedback data regarding pressure and time at which the inflation fluid is introduced into the balloon is also provided using sensors.
For example, in U.S. Pat. No. 5,599,301 a motor controller for providing a constant rate of pressure change during inflation and deflation of an expandable member of a catheter for use in a body lumen by an automated inflation system is disclosed. The system conforms the rate of change of pressure to a set point value by means of a feedback loop controller, and makes possible consistent inflations and deflations using an automated system regardless of variations in catheter volume and compliance characteristics. Safety features such as maximum pressure and balloon rupture alarms are also disclosed.
Various improvements of sensing systems for catheter inflation systems have been suggested, for example in U.S. Pat. No. 5,891,089 disclosing a fluid pressure sensing and activating control system for coronary angioplasty, including a fluid pressure sensor and transducer connected to feed signals via an A/D converter to a processor and control unit, a pulse width generator receiving signals from the processor for activating a balloon inflator, and a fluid conduit connector attached to the output of the inflator and to the input of the fluid pressure sensor and transducer, and having a further output port connectable to an inflatable balloon. A method for dilating a section of an elastic conduit by means of an inflatable balloon inserted therein is also disclosed.